You’re relying on a 50 year old gauge to be accurate. You need a direct reading off the engine to rule out that possibility. IMHO

why don't you just but an infrared heat gun and point it to the thermostat housing and radiator and read the temp? it will give you an idea if your Guage is off that much.

Do you have a working choke lever? In the "stumbling" situation have you ever tried adding a bit of choke? The choke on the SU carbs will enrichen the fuel mixture. Your plugs don't look like they suffer from an excessively rich condition. In my opinion you're overly focused on coolant temperature and that damn gauge...

Does your mechanic know how to set the initial needle position for ambient temperature and altitude on the carbs? (there are knobs on the bottom of each carb that control initial needle height) Or how to balance (synchronize) SU carbs? It's all in the Factory Service Manual.

7 hours ago, cgsheen1 said:

Do you have a working choke lever? In the "stumbling" situation have you ever tried adding a bit of choke? The choke on the SU carbs will enrichen the fuel mixture. Your plugs don't look like they suffer from an excessively rich condition. In my opinion you're overly focused on coolant temperature and that damn gauge...

Does your mechanic know how to set the initial needle position for ambient temperature and altitude on the carbs? (there are knobs on the bottom of each carb that control initial needle height) Or how to balance (synchronize) SU carbs? It's all in the Factory Service Manual.

7 hours ago, cgsheen1 said:

Do you have a working choke lever? In the "stumbling" situation have you ever tried adding a bit of choke? The choke on the SU carbs will enrichen the fuel mixture. Your plugs don't look like they suffer from an excessively rich condition. In my opinion you're overly focused on coolant temperature and that damn gauge...

Does your mechanic know how to set the initial needle position for ambient temperature and altitude on the carbs? (there are knobs on the bottom of each carb that control initial needle height) Or how to balance (synchronize) SU carbs? It's all in the Factory Service Manual.

Im the one setting the fuel jets to 3.5 turns clockwise. Not wasting more money or time with camaro or porsche mechanics. I even asked the camaro mechanic to reimburse the usd300 i paid him for labour. I did the ground test on the stock gauge and the needle moved to the right so it should be fine. Do you want me to do the choke test when stuck in traffic?

Edited July 20Jul 20 by 72 Datsun 240z

All that tells you is the gauge is not dead. Has nothing to do if it’s calibrated correctly. Same applies to the fuel gauge.

Best of luck with your problem, hope you get it sorted one day.

2 hours ago, Yarb said:

All that tells you is the gauge is not dead. Has nothing to do if it’s calibrated correctly. Same applies to the fuel gauge.

2 hours ago, Yarb said:

All that tells you is the gauge is not dead. Has nothing to do if it’s calibrated correctly. Same applies to the fuel gauge.

12 hours ago, Yarb said:

All that tells you is the gauge is not dead. Has nothing to do if it’s calibrated correctly. Same applies to the fuel gauge.

How else can i verify the current temp? Will i need to adapt or customize an external temp gauge?

Any other way of measuring the temp correctly?

so why don't you remove the radiator cap when the engine is cold and start the engine let it warm up. now make sure the coolant is low enough to not overflow. let the thermostat open and insert a meat thermometer the opening and be careful not touch the sides, insert 1-2 inches and then take a reading.

Buy an IR gun like this

All kinds of uses. When your car is good and warm, shoot the thermostat housing and verify against the gauge . When the car acts up in traffic, scan the carbs, float bowls, fuel rail, etc to see if something is unusually hot

On 7/21/2026 at 4:09 PM, Patcon said:

Buy an IR gun like this

All kinds of uses. When your car is good and warm, shoot the thermostat housing and verify against the gauge . When the car acts up in traffic, scan the carbs, float bowls, fuel rail, etc to see if something is unusually hot

Thanks ill get one from amazon! Any brand??

No, any brand.

They're likely all Asian and they should be fairly cheap with a laser pointer